1. Field of the Invention
The present invention relates to equipment for rod strings, such as a drill pipe string, including a side entry sub for passing a cable from the inside towards the outside of the pipes, with hydraulic sealing about the cable.
Side entry subs are well known by oil drilling specialists. Such a device is described for example in the British Patent No. 2 135 719.
2. Description of the Prior Art
A side entry sub is described for example in the technique described in French Patent No. 2 501 777 and its first two additions FR-A-2 522 059 and FR-A-2 564 893.
In this technique, which makes it possible to carry out logging or work in horizontal or very slanted wells, a well logging probe (or work tool) is initially fixed to the lower end of a pipe string which is lowered into the well as it is formed.
Then an electric cable, is lowered inside the pipes, by gravity and by pumping. The cable has a weighted connector (the connector having a load bar mounted thereover) which is connected to a complementary connector fixed to the top of the probe (or tool). In the portion of the drill pipe string corresponding to the vertical or slightly slanted portion of the well, a side entry sub allows the cable to be passed from the inside to the outside of the drill pipes.
Recording of the measurement (or work in the well) is carried out by moving the whole of the drill pipe string from the surface.
The equipment with side entry sub used at the present time cannot be used when the dimensions of the well are too small. This occurs more particularly when a small diameter bore hole has been cased.
In providing compact equipment which overcomes this difficulty, the present invention provides a connection allowing fluid flow in the lower portion of the drill pipe string, for the purpose of moving parts, tools, load bars . . . connected by a cable to the surface installations.